High frequency tube structure



Feb. 23, 1943. w. w. HANSEN Emu.- 2,311,658

HIGH FREQUENCY TUBE STRUCTURE Filed July 2, 1940 5 Sheets-$heet 1INVENTORS. lA/ILL [AM W HANSEN,

Russ-Eu. H. VAR/AN,

6/ u 0 VAR! N. g av A may.

Feb. 23, 1943. w. w. HANSEN ETAL.

HIGH FREQUENCY TUBE STRUCTURE Filed July 2, 1940 5 Sheets-Sheet 2.INVENTORJ, WILLIAM W HANSEN. Husszu. H. VAR/AN, 5/ UR E VAR AN BY V MATT RNEY.

HIGH FREQUENCY TUBE STRUCTURE Filed July 2, 1940 5 Sheets-Sheet 4 F/CT.5

I01 INVENTORS,

\A/ILLIAM W HANSEN.

Russzu. H. VARIAN.

Feb. 23, 1943. w w HANSEN ETAL 2,311,658

1mm mmmuc'r TUBE swans-runs Filed Jul 2, 1940 5 Sheets-Sheet 5 SIG- RDVAR! N.

ATT RNEY.

Patented Feb. 23, 1943 HIGH FREQUENCY TUBE STRUCTURE William w. Hansen,Russell a. Varian, and Sigurd F. Varlan, Stanford University, CaliL,

asst

gnors to The Board oi Trustees of the leland Stanford, Junior,University. Stanford University, Calil'., a corporation of CaliforniaAppllcationJuly 2, 1940, Serial No. 343,528

17 Claims.

This invention relates, generally, tohigh irequency tube structureshaving enclosed oscillatory circuits of the type disclosed in Patent No.2,242,275, issued May 20, 1941, in the name of Bussell H, Varian, one ofthe inventors herein, and the invention has reference more particularlyto novel improvements in this type of structure operating at frequenciesof the order of cycles per second.

The principal object of the present invention is to provide a novelpracticable embodiment of high frequency tube structure utilizingprinciples disclosed in the above identified application, the device ofthe present invention employing a pair of hollow resonators and beingoperable not only as a self-oscillator but also as an amplifier anddetector. at will.

Another object of the present invention lies in the provision of anoveltube structure wherein the resonant circuits are provided withnovel tuning means for eii'ecting either individual or gang tuning ofsaid resonant circuits.

Another object of the invention is to provide a nigh frequency tubestructure having hollow resonators provided with concentric lineterminals having energy transfer loops extending into the interiors ofsaid resonators for selectively removing energy therefrom or deliveringenergy thereto, said concentric line terminals being adapted to haveconcentric lines removably attached thereto for effecting use of thistube structure either as an oscillator, amplifier, or detector,whichever is desired.

Still another object of the present invention is to provide a novel highfrequency tube having the elements thereof rigidly supported so as tomini mize microphonic noises during the operation of the tube.

Other objects are to provide a novel non-magnetic emitter heater coiland to provide a novel and easily assembled grid structure.

Other objects and advantages will become apparent from thespecification, taken in connection with the accompanying drawingswherein the invention isembodied in concrete form.

In the drawings,

Fig. 1 is a longitudinal view partly in section of one embodiment of theinvention.

Fig. 2 is an end view partly broken away of the apparatus of Fig. l.

Fig. 5 is a cross-section along the line 5-5 of Fig. 3.

Fig. 6 is a longitudinal cross-section of a modi fled structure.

Fig. '7 is a longitudinal view partly in section of a modifiedstructure.

Fig. 8 is a sectional view taken along line 8-8 of Fig. 7, and Figs. 9,10, 11 show details.

Similar characters of reference are used in all of the above figures toindicate corresponding parts.

Referring now to the drawings, the novel tube structure is shown in Fig.1 comprising a central tubular shell i, having spaced hollow resonators2, 3 contained therewithin that are secured at their peripheries to theinner wall of shell i. Resonators 2, 3 form enclosed electron-excitableresonant circuits of the type disclosed in Patent No. 2,242,275. Thesecavity resonators are shown of toroidal or substantially doughnut shape,the inner walls terminating in opposed grids I, 5, and B, I. The wallssupporting grids 5 and 6 are shown interconnected by a central tube 8.The wall supporting grid 4 is connected by a tube 9 to an end plate III,which supports a tubular membe:- H to which an end bell l2 of glass isfastened by a metal to glass seal 13. Similarly, the wall supportinggrid I is connected by a tube H to an end plate l5 which supports atubular member ii to which an end hell I! of glass is fastened by ametal to glass seal IS.

The end bells i2 and II, the cavity resonators 2 and 3, and connectedaligned tubes 8, 9 and I4 are evacuated, the bell l2 being sealed off,as at l9. End bell l2 contains an electron emitter structure 20, havingan electron emitting surface 21 heated by a filament 22, having supplyleads 23 and 24 passing through a press 25 supporting the electronemitter structure 20. Emitter structure 20 is shown arranged andconstructed so as to minimize heat losses in undesired directions. Theelectron emitter structure is so arranged, as with a projecting ring 26,that the electrons emitted from surface 2| are collimated into a streamthat will pass through the grids 4, 5, 8 andl.

End bell [2 contains the getter coils 21, 28 with end leads 2! and 30passing through press 25 and a center lead 3| which may be connected tof lament lead 23. While not essential, these getter coils of suitablematerial, such as zirconium, are

' preferably heated to difierent temperatures to Fig. 3 is alongitudinal view partly in section of a somewhat modified structure.

Fig. 4 is a cross-section with parts broken away along the line 4-4 ofFig. 3. v

control the vacuum. Thus, coil 21 may be heated to approximately 400 C.for absorption oi hydrogen. and coil 28 may be heated to approximately1700 C. for absorption of other gases, such as oxygen and nitrogen. Alead I! passing through end bell i1 supports a collecting plate elementIt Grid 34 is an accelerating grid, and grid ii is used to obtain a moreuniform electrostatic field.

The structure of Fig. l is shown connected for serving as an oscillator,although by changing the connections, the same may be made to serve asan amplifier and if desired, also as a detector. In this figure, hollowor cavity resonator I acts as a "catcher" for electromagnetic energy andis back coupled to cavity resonator 2 acting as a "buncher" by means ofa concentric line 36 terminating in loops 31 and 38, as is disclosed inthe above mentioned patent No. 2,242,275. A concentric line terminalpost 38 extends through an aperture provided in shell I and is attachedto catcher" resonator 3. This concentric line is provided with a loop 40extending into the oscillating electromagnetic field within-resonator 3for the purpose of removing energy therefrom. The outer end ofconcentric line terminal 39 is sealed as by a glass bead II. Aconcentric line ll is adapted to be removably connected to terminal post39 for the purpose of conveying the energy to any desired point, as to aradiating antenna.

Atmospheric pressure, acting upon the outer end walls of cavityresonators 2 and 3 supporting grids 4 and I, tends to cause these wallsto deflect longitudinally inwardly so that grid 4 tends to approach grid5, and grid I tends to approach grid 6. The amount of deflection ofthese grids under the effect of atmospheric pres sure is controllable atwill by the use of the novel tuning means of this invention. This tuningmeans comprises end plates Hi and II that are rigidly connected to'tubes9 and I4 respectively. Inward movement of end plates in and I5 ismicrometrically controlled by means of struts l2 and I4. three of whichstruts are used in connection with each of the plates ill and IS, thestruts being spaced angularly 120 apart. These struts have pressureballs 43 at the ends, which bear respectively upon adjustable screws 60carried by end plates l and BI, and upon socket bearings it carried inring members SI! and ii that are tumably mounted upon collars l1 and 48fixed upon central shell I, as by a bolt 49. A thrust ring is rigidlymounted upon central shell i is engaged by balls 53 carried by retainersM and 55, which balls in turn bear against the socket bearings l tothereby transmit the thrust of struts i2 and H to stationary thrust ring.6.

A yoke 56 is fastened to rings ill and SI, and a lug 52 is fastened tothrust ring 48. Members 51 and 56 are (see Fig. 2) urged toward eachother by a coil spring 58, and are held apart by a strut 51 havingpressure balls 43 at its ends which bear into depressions provided inyoke 58 and in an adjusting screw is threaded through lug 52, as shownin Fig. 2. When screw 59 is adjusted, ring members 50 and il are causedto turn relative to stationary thrust ring 8 causing the angularpositions of struts "and H to be altered at will, thereby varying thedistance between end plates III and I5 and stationary thrust ring 46,and hence effecting relative movement of grids 4 and I with respect tostationary grids i and i, thereby altering the tuning of the resonators,i. e., effecting the gang tuning thereof.

The positions of end plates l0 and I5, and hence the position of grids Iand 1, are initially adjusted by means of the screws ill and lock nutsill, while the angularity of the struts l2 and 44 is adjustable as agroup by means of screw 58.

End plate II comprises an outer ring ll which is mounted tofrotate withrespect to an inner supporting ring I. Headed screws I! are threadedinto ring I! and are adapted to engage outer ring CI for locking thisring in desired angular position upon supporting ring 02. A cam plate 64is fixed upon supporting ring 82 and has a slot 85 therein cooperatingwith an eccentric G1 which is fixed upon a bolt l8 tumable in anaperture provided in outer ring II. with screws ll loosened, then byturning bolt 80, eccentric 01 cooperates with cam plate ll to turn ring8| relative to supporting ring I, thus changing the angularity of allthe three struts M similarly, and eifecting the individual tuning of"catcher" resonator I. Thus, "catcher resonator I can be tuned readilyto buncher" resonator 2. It is desirable to adjust screws ll so thatwhen resonators I and 5 are adjusted to resonance, the

angularity oi struts I! will be substantially the same as that of strutsN. This will'perrnit gang tuning of resonators 2 and 3 by means ofadjusting screw as over the widest possible range. Owing to the toggleaction of struts l2 and N, a very minute adjustment of the frequency ofthe resonators 2 and 3 is easily attainable, thereby readily tuningthese resonators together, or with other resonators if desired, even atthe high frequencies of the order of 10 cycles per second at which thepresent device is intended to operate. The value of this tuningmechanism will be realized when it is noted that a relatively largemovement of rings 50 and it produced through turning screw 58 eifectsbut a slight change in the spacing of the grids l! and 8-1.

The form of the invention of Fig. 3 is similar to that shown in Fig. 1,except that instead of the tuning mechanism operating to adjust theangular position of all the struts simultaneously this apparatus is setup to adjust only one strut 92 and one strut 92' simultaneously, theremaining struts being unadjusted by the gang tuning equipment of thisfigure. Also, the tube 0! Fig. 3 is shown operating as a receiver, thesame being provided with grids II and II for eifecting detection. Endbell l1 contains the getter coils 21 and 28 and a cylinder 10 carryinggrids H and 1!. Cylinder l0 surrounds and shields plate element 33 andis maintained through supply lead II at such a voltage that a part ofthe electrons passing grid 35 will be reflected by grids II and 12 andhence are prevented from reaching plate element 83. Grid II ispreferably placed at an angle to the axis of the tube to prevent thereflected electrons from again passing through grid I. The number ofelectrons reaching plate element 3% can thus be made to vary with thestrength of electromagnetic oscillations in cavity resonator 3,resulting in detection oi such oscillations.

The supply leads for getter coils 21, 28 are brought out through press25' at a, an and u',

surrounding plate lead 32, thus serving to shield lead 32, as shown inFig. 5.

The buncher renonator 2 in this form of the invention is equipped with aconcentrig line terminal post 39 adapted to be connected to a receivingantenna for supplying the signal to resonator 2. Additional concentricline terminal posts are shown attached to-the buncher" and catcher"resonators for the purpose of altering the functions 01' the tube, whendesired. Thus, if a terminal post 39 of the "catcher" is coupled back asby a concentric line to a terminal ost l! or the buncher." the apparatuswill serve as an oscillator. v

This tube structure is also shown Provided with a space charge controlgrid as when modulation is desired. this grid being shown provided witha terminal lead 88. This grid is shown carried by tocussing ring III,which in use would normally have a collimating efl'ect upon the electronstream.

In Fi 3 end plates III and II are urged toward each other by springs It,the thrust of the springs It, in addition to that produced by,atmospheric pressure, being resisted-by struts I2, 92' and 83, 02. Threepairs of substantially aligned struts angularly spaced 120 apart areused. Of these. two pairs of struts 93, II rest directly upon stationaryring 00, whereas the remaining pair of struts 82 and I! bear upon theouter sides of the arcuate levers l4 and I4 that are pivoted at I! onstationary thrust ring 06, as seen in Fig. 4.

The thrust of strut 02 is transmitted to lever 94 and then through ball03 constrained to move in a race It concentric with pivot 15 tostationary thrust ring 46. The thrust of strut 82' is simi larlytransmitted through lever 9| to ring It. Levers 04 and N are fastenedtogether by a yoke 95. A lug I8 is fastened to thrust ring 46 andthreaded for an adjusting screw 01. A coil spring 90 urges members 05and 06 toward each other and these members are held apart by a strut 99.By adjusting screw 91, levers SI and 94' are caused to rotate aboutpivot 15, thereby changing the angularity of struts 02 and 92' andcausing the end plates I0 and II to tip slightly relative to stationarythrust ring I. This tipping of the end plates changes the averagespacing of grids l and 5 of the buncher" and grids I and 8 of the"catcher," eil'ecting an alteration in the gang tuning of these hollowresonators.

Grids 4, 5, i and I are shown shaped like very shallow cones with theirapexes facing each other. The electrostatic field between opposed grids45 and 0-1 is of such a nature that low velocity electrons are caused tomove radially outward and beyond the strong electrostatic field existingbetween these opposed grids, where the presence of such electrons may beundesirable.

The inner walls of both cavity resonators 2, 3. supporting grids 5 and'!are oi large cross-seclion and thereby serve to readily transmit theheat generated in grids 5, 0 to central shell I. wherefrom it may bedissipated in a known manher. The cross-section of the electron pathbetween grids 5 and i is enlarged transversely of the stream whichstructure minimizes diffusion of the electron stream due toelectrostatic forces.

In Fig. 6 the end shells II and I6, and their associated parts, aremodified to provide an extremely rigid mounting for the various elementsto minimize microphonic noises. In this figure, the space charge controlgrid 60 is carried by a tubular member II, which is rigidly attached toshell II and spaced in concentric relation therewith by a seal I9.Similarly, the emitter structure 20 is carried by a tubular member II,which is rigidly supported in concentric relation to tube II by glassseal 80. Also, the filament lead IIII is attached to a. tube 85, whichis rigidly held in concentric relation to tub II by means 01' a seal 84.Tube 80 is sealed by a glass bead 88. In this manner the electronemitter assembly is rendered extremely rigid to minimize microphonicnoises. Similarly, the tube carrying th detector grids II and I2 isrigidly supported cona,a11,oss

Iii

-rectly against stationary thrust ring it.

centrically with the shell I! by means oi a glass seal II'. Also theplate element 38 is rigidly supported in isolating relation with respectto a tube ll fixed by seal 81 concentrically with respect to tube ll.

In the structure shown in Fig. 6, wherein in operation it is generallyonly necessary to tune one resonator to the other, gang tuning is notillustrated. Instead, three pairs oi struts 93 and 83 are used whichbear at their inner ends di- The frequency adjustments are made byadjusting the screwsil.

Thus. it will be seen that tuning means is provided in the severalfigures. not only eflectini; gang tuning of the resonators, as byangularly adjusting all three Pairs of struts simultaneously as shown inFig. 1'. or by adjusting a single pair of struts. as shown in Fig. 3, orif desired, individual strut adjustment may alone be used. as shown inFig. 6.

In the form of the invention shown in Figs. 7 to 10, the hollowresonators I0! and I04 are shown carried by the inner ends of tubularmembers I05 and Ill. The inner opposed and walls I01 and ill ofresonators I03 and I00 are annularly corrugated and flexible and carry adrift space providing tube I09. A collar 0 is shown fixed on tube Illand has a ring member III turnably mounted thereon. Anti-friction endthrust bearings I I2 are shown interposed between member III and collarIIII. washer 3 may be interposed between collar 0 and one 01' thebearings H2. Three pairs of spaced tuning struts Ill and III are showninterposed between the opposite sides of ring II I and screw plugslllcarried by end plates H8 and Ill fixed on tubular members I05 and I00.

A tuning screw III is threaded through a lug II! provided on collar II!and acts through a strut I20 to engage ring III for turning the lather.A return tension spring Iil connected between ring III and lug H9eliminates back-lash. By turning screw II! the ring III is shifted orturned angularly with respect to tube I 0! causing toggle struts I" andIll to move collars III and I" toward or away from one another as thecase may be, thereby deflecting end walls I01 and I00 of the resonatorsto eflect the gang tuning thereof. This tuning arrangement employing thesingle ring III may be used in the preceding figures oi the drawings ifdesired. Individual tuning adjustment or the resonators I03 an: I" maybe accomplished by adjusting screws If desired, external tuningresonators I20 and III may be used for tuning resonators I03 and I04from a remote point. Resonators I20 and I2i are shown connected byconcentric lines I22 and I23 to resonators I03 and I04, respectively.loops I24 at the ends of the lines serving to link the resonant fieldswithin the resonators. Tuning resonators I20 and III are provided withsuitable variable impedance means shown as a loop I25 in resonator I 20and as a plate I28 in resonator I2I which loop and plate are tumable byknobs I21 and I21. By turning these knobs the frequency of oscillationwithin resonators I20 and HI is varied thereby effecting a variation inthe frequency of the connected resonators I03 and I04. Obviously whenthe remote tuning resonators I20 and HI are employed the local tuningmeans lit-4H may be omitted, if desired. Also if this local tuning meansis used. a remote tuning means may be omitted if desired. The

A thrust spring length of the concentric lines I22 and I2! is variabledepending on the location of resonators I25 and Iii. Actually the tuningof resonators lb! and llll may be eilected by varying the length oflines I22 and I23. 1

The outer ends of resonators III and! I are shown formed by the use ofdished plates I28 and I29. By using dished plates instead of flat disks,variations in tuning due to thermal expension and contraction aregreatly reduced. The plates I28 and III and the ends of tube I" carrygrids I30 for operating on the electron stream. These grids, asillustrated in Fig. 9, may be formed out of a metal ribbon, as by theuse of suitable dies, and then folded to shape. Thus, in Fig. 9, thegrid is shown or cruciform shape having angular indentationsinterconnected by arcuate portions and produced from a single ribbon orcopper, for example, which grid is set into the apertures of membersI25, I28 and m. The spring tension of these grids will hold them inplace while the same are being welded or otherwise secured permanentlyin place, thereby facilitating the assembly of these grids in theresonators. Although these grids are shown of cruciform shape havingfour internal projections, the same may be formed with a greater or evenlesser number of internal projections if desired, the main idea beingthat the same is formed from a continuous ribbon of metal that isdeformed to the desired shape.

If desired, mica {disks I32 may be interposed between the emitter andthe glass press carrying the same and between the electron collector andthe press carrying such cpllector. Such a disk, shown in Figs. '1 and 8,not only prevents excessive heat from reaching the glass press but thesame is so supported as to prevent shorting oi leads by the presencethereof. Thus, in Fig. 8, the disk I32 is shown carried by dead endleads or wires I331 which wires pass snugly through apertures in thedisk. Apertures I in disk I accommodating the live leads are made largeas shown in Fig. 8 so as not to touch the live leads. Thus any volatileconducting material, produced as by heating of the electron catcher oremitter in use, upon condensing on the mica disk I32 does not short thelive leads, which would otherwise happen were the apertures IN the samesize as these live leads.

A novel type of emitter heating coil or winding is shown in Fig. 10.This winding is formed by first doubling the heater wire upon itselfthereby forming two strands or wires I35 and I35 connected at one end bya loop I". The looped wire is then wound around two somewhat spacedfixed pins as shown in Fig. 11, thereby forming a series of figure 8's,(see also Fig. 10). To cover the wire with a suitable insulator, it ismerely necessary to separate the ends I35 and I35, the several figure8's separating readily, forming two sections connected by loop I36 andenabling the wire to be completely coated with insulating material, suchas aluminum oxide. The two sections of the heater coil are then againclosed as shown in Fig. 10 and then folded or turned upon themselvesinto a cylinder for sliding into the hollow interior of the emittercasing I89. The end llli of the emitter casing is coated with a suitableemitting oxide. The emitter heating coil, as thusly produced, not onlyis non-magnetic, since the two wires I55 and I35 carry the currents inopposite directions and do not influence the electron stream leaving thefront the emitter, but this type of construction also enables all of thewire surfaces to be uniformly coated with insulating material andprevents shorting of portions of the wire which would take place werethe same merely wrapped around a single pin or cylinder.

As many changes could be made in the above construction and manyapparently widely diffferent embodiments 01 this invention could be madewithout departing from the scopethereof. it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A high frequency tube structure comprising a shell, a hollowresonator carried by said shell, an end plate disposed adjacent saidshell and connected to said resonator, and tuning means comprisingtoggle mechanism interposed between said end plate and said shell, saidend plate having means for angularly shifting said toggle mechanism foreifecting the tuning of said resonator.

2. A high frequency tube structure comprising, a tubular shell, a pairof spaced hollow resonators contained within said shell and carriedthereby, a pair of end plates disposed adjacent to the opposite ends ofsaid shell and connected respectively to said resonators, and tuningmeans comprising toggle mechanism interposed between said shell and saidend plates for effecting simultaneous movement of said end plates withrespect to said shell. to cause simultaneous distortion of saidresonators and effect the gang tuning thereof.

3. A high frequency tube structure comprising, a tubular shell, a pairof spaced hollow resonators contained within said shell and carriedthereby, a pair of end plates disposed adjacent to the opposite ends ofsaid shell and connected respectively to said resonators, and tuningmeans comprising toggle mechanism interposed between said shell and saidend plates, said toggle mechanism comprising angularly adjustable ringsturnably supported on said shell, toggle struts interposed between saidrings and said end plates and screw means for simultaneously 7 turningsaid rings.

4. A high frequency tube structure comprising an open ended shell, apair of spaced hollow resonators within said shell and carried thereby,said resonators having flexible walls adjacent the ends of said shell,end plates positioned adjacent the ends of said shell and connected tothe flexible walls of said resonators, and tuning mechanism connected tosaid shell and said end plates, said tuning mechanism comprising athrust ring carried by said shell, anti-friction thrust bearingsengaging said thrust ring. toggle struts in terposed between said thrustbearings and said end plates, and means for angularly shifting saidtoggle struts to vary the distance between said end plates and effectingthe tuning of said resonators by deflecting the flexible walls thereof.

5. A high frequency tube structure comprising a shell, a hollowresonator carried by said shell, an end plate disposed adjacent saidshell and connected to said resonator, and tuning means comprisingtoggle mechanism interposed between said end plate and said shell, saidend plate having means for angularly shifting said toggle mechanism forcheating the tuning of said resonator, said angular shifting meanscomprising an eccentric for angularly shifting a nortion of said endplate to cause the angular shiitlng of said toggle mechanism.

6. A high frequency tube structure comprising a cylindrical shell,spaced hollow resonators within and attached at their peripheries tosaid shell, said resonators having reentrant central portions, endplates disposed on opposite sides of said shell and having tubularprojections connected to the reentrant central portions of said shells,an emitter for directing electrons through said resonators by way ofsaid tubular projections, and electron collecting means, one of said endplates having an additional tubular projection rigidly supporting saidemitter and the other of said end plates having an additional tubularprojection rigidly supporting said electron collecting means.

7. A high frequency tube structure comprising hollow resonator means. anemitter for producing an electron stream for passage through saidresonator means, a modulating grid interposed between said emitter andsaid resonator means for modulating the electron stream, tubularsupports carrying said emitter and said modulating grid, and vitreoussealing means interposed between said tubular supports and between saidsupports and said resonator means and rigidly supporting said emitterand modulating grid with respect to said resonator means.

8. A high frequency tube structure as defined in claim 7, wherein adetector grid is provided for changing the velocity of electrons leavingsaid resonator means, a tubular support carrying said grid, vitreousmeans interposed between said tubular support and said resonator meansrigidly supporting said detector grid with respect to said resonatormeans.

9. A high frequency tube structure comprising a hollow resonator, saidresonator being apertured for receiving a concentric line terminal post,said terminal post comprising a tube member extending into the apertureoi said resonator and secured thereon, a lead disposed centrally withinsaid tube member, a vitreous seal between the outer portion of said tubemember and said central lead, and a loop provided on the inner end ofsaid lead projecting into the interior of said resonator and connectedto said tube member.

10. A high frequency tube structure comprising a cylindrical shell.hollow resonators provided at the end portions said shell, end platesattached to said resonators and extending radially beyond said shell, athrust member provided on said shell, adjustable screws carried by saidend plates, and toggle struts interposed between said screws and saidthrust member, the adjustment of said screws eil'ecting relativemovement between said end plates and said thrust member to therebyeilect tuning of said resonators.

ii. A high irequency tube structure comprisin a cylindrical shell,hollow resonators provided at the end portions of said shell, end platesattached to said resonators and extending radially beyond said shell. athrust member provided on said shell.levers pivoted on opposite sides ofsaid thrust member, toggle struts interposed be tween said levers andsaid end plates, and screw means interposed between said levers and saidend plates, and screw means interposed between said levers and saidshell for angularly moving said levers to eflect relative movement ofsaid end plates with respect to said thrust member,

thereby distorting said resonators and tuning the same.

12. A high frequency tube structure comprising hollow resonator means,an emitter for producing an electron stream for passage through saidresonator means, a coilimating ring interposed between said emitter andsaid resonator means for concentrating the electrons of said stream intoa beam, and a modulating grid carried by said collimating ring formodulating said electron stream.

13. A tube structure comprising a pair of spaced resonators, end platesattached to said resonators, tubular means interconnecting saidresonators and providing a driitispace therebetween, adjustabledisplacing means carried by said tubular member and struts interposedbetween said displacing means and said end plates. the adjustment ofsaid displacing means effecting movement of said struts and relativemovement or said end plates thereby deflectinge walls of said resonatorsto gang-tune the same.

14. A tube structure comprising an emitter casing, a cathode heater coilwound annularly therein, said coil comprising a series of il-shaped coilwindings, the adjoining windings of said coil for carrying currents inopposite directions to thereby render the coil non-magnetic.

15. The method of forming an emitter heating coil comprising bending awire upon itself, winding the thusly bent wire about two spaced pins toform l-shaped convolutions, separating said convolutions by pulling thefree ends of the wire apart, applying insulating material to thewindings and again assembling the windings together.

16. A hollow resonator comprising a body having an electron beamaperture therein, a grid retained in said aperture; said grid comprisinga deformed strip of metal, said deformed strip having alternate arcuateportions conforming to the perimeter of said aperture, said arcuateportions being of substantially the same curvature as said apertureperimeter, and intervening V- shape portions projecting toward thecenter of said aperture.

17. An electron discharge tube comprising means for producing anelectron stream, a hollow resonator spaced therefrom. and detector meanscomprising a pair of spaced grids in the path of said electron streambeyond said resonasaid grids being conductively connected to- Eether soas to be at substantially the same potential for providing asubstantially iield free space therebetween.

WIILIAMW. HANSEN. RUSSEL- H. VARIAN. SIGURD 1". VAR-IAN.

